assignment bio

PENANG MATRICULATION COLLEGE
BIOLOGY
SB 015

SEMESTER 1, SESSION 2022/2023

MOLECULES OF LIFE & CELL
STRUCTURES AND FUNCTIONS

NAME : NUR NADIAH BINTI RADZI
MATRIC NUMBER : MS2113172738
PRACTICUM : H8T04A
LECTURER’S NAME : IFRIZAMUNIRAH BINTI IBRIM@IBRAHIM

Main types of molecules of life

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Classify carbohydrates into three main classes based on their
structure and characteristics.

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INDEX Human are unable to digest vegetables, but herbivors are able
Set B but, herbivors are able to do so. Explain this statement by
focusing on a significant structure of the plant cell.

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Name the organelle which synthesizes carbohydrates in plant

cells. Describe how the organelles structures are involved in the

synthesis of carbohydrates.

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Reference 10

WATER

CARBOHYDRATES

PROTEINS

MAIN TYPES
OF

MOLECULES
OF LIFE

DNA and RNA molecules LIPIDS

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Classify carbohydrates into three main classes based
on their structure and characteristics.

CARBOHYDRATES

MONOSACCHARIDES DISACCHARIDES POLYSACCHARIDES

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MONOSACCHARIDES

• Monosaccharides is a simple sugars that cannot be broken down into smaller

molecules by hydrolysis.
• Monosaccharides can be the monomers for disaccharides and polysaccharides.

1. Characteristics eg: glucose (C6H12O6)
• Sweet-tasting
• Soluble in water
• Can be crystallised
• Reducing agent: has a free ketone or aldehyde group, can denotes electrons to other

molecules

2. Structure
• Straight-chain form, ring form in aqueous
• A sugar has : i) a carbonyl group ( C=O )

ii) many hydroxyl groups ( -OH )

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DISACCHARIDES

• Disaccharides is a double sugar molecule that consists of 2 monosaccharides.
-Linked by glycosidic linkage
-Glycosidic linkage is a covalent bond formed between two monosaccharides by
a condensation reaction.

1. Characteristics

• Sweet

• Water soluble eg: Formation and breakdown of Maltose

• Can be crystallised

• Reducing agent : depend on free functional group (aldehyde & ketone) at sugar structure

2. Structure eg: maltose (a-glucose + a-glucose)
• A double sugar molecule : consists of monosaccharides
- Linked by glycosidic linkage / bond 6
- Glycosidic linkage: covalent bond formed between two

monosaccharides by a condensation reaction

POLYSACCHARIDES eg: Cellulose
eg: Cellulose structure
• Polymers formed when hundreds of monosacsharides joined by glycosidic
linkage (through) condensation).

• Breakdown by hydrolysis.

1. Characteristics
• Large/ macromolecule / complex
• Not sweet
• Insoluble in water
• Cannot be crystallised

2. Structure
• Polymers formed when hundreds of monosaccharides joined by glycosidic

linkages (through condensation)
• Breakdown by hydrolysis
• The chain formed by:
i. Variable in length
ii. Branched or unbranched
iii. Folded : ideal for energy storage
iv. Straight or coiled

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HUMAN ARE UNABLE TO DIGEST VEGETABLES, BUT HERBIVORS ARE ABLE TO DO SO. EXPLAIN THIS
STATEMENT BY FOCUSING ON A SIGNIFICANT STRUCTURE OF THE PLANT CELL.

• Cell wall is a non-living structure that surrounded the cell membrane
• In a plant cell, the cell wall is made up of cellulose, hemicellulose, and proteins while in a fungal

cell, it is composed of chitin.
• Beta glucose is the monomer unit in cellulose.
• Cellulose is a linear homopolymer of glucose monomers formed by condensation

polymerization; β-(1-4) glycosidic bonds connect monomers forming long chains which

crystallize into dense sheets.

Digestion of Cellulose in Humans Digestion of Cellulose in Animals

• Cellulose is polysaccharides found in plants and contain ß-1,4 • Termites have mastigophorans (microbes) in their gut which

glycosidic bonds in the structure it can breakdown by enzyme brings about the digestion of cellulose.
• Herbivorous animals, on the other hand, are ruminants. They
cellulase.
• Human cannot synthesize the cellulases enzymes which can have different compartments in their stomach to carry out

break ß glycosidic bond. digestion.
• So, cellulose is not digest in humans. • The rumen is the first compartment where ingested food
• Therefore this is secreted as unbroken down chains of glucose
containing cellulose is stored temporarily and later regurgitated
called fiber.
to chewtheir cud.
• They are able to digest cellulose because of the presence of 8

bacteria and enzymes cellulase in the rumen where anaerobic

bacterial digestion occurs.
• This microorganism help to breakdown the cellulose, which

digest the vegetables in gut.
• A by-product of this type of digestion releases methane which is

foul-smelling and causes the destruction of the ozone layer of

the Earth.

Name the organelle which synthesizes carbohydrates in plant cells. Describe
how the organelles structures are involved in the synthesis of carbohydrates.

• Organelle that synthesizes carbohydrates in plant cells are chloroplast.
• Chloroplasts are chlorophyll-containing organelles found in plants, algae, and

cyanobacteria. Photosynthesis occurs in chloroplasts.
• Chlorophyll is a green photosynthetic pigment within the thylakoid membrane that

absorbs light energy for photosynthesis.
• Chloroplasts are found in plant leaves surrounded by guard cells. These cells open

and close tiny pores allowing for the gas exchange needed for photosynthesis.

LIGHT REACTION CALVIN CYCLE

• It occurs in the thylakoid membrane of the • It occurs in stroma of the chloroplast.
• It occurs in the presence or absence of light.
chloroplast. • Calvin cycle absorbs only CO2.
• It occurs only in the presence of light. • End product is glucose.
• Light reaction absorbs oxygen and light energy. • Carbon fixation occurs.
• End products are oxygen, ATP and NADPH. • Second stage of photosynthesis.
• Photolysis of water occurs.
• First stage of photosynthesis.

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REFERENCE

1. Sushil Humagain. ( 17 October 2018 ). Amino acids: General properties and classification.
o https://onlinesciencenotes.com/amino-acids-general-properties-and-classification/
2. PSIBERG Team. (2 January 2022). Alpha(α) and Beta(β) Glucose: Comparison, Structures.
o https://psiberg.com/alpha-and-beta-glucose/
3. Allison Soult. (22 February 2022). Lipids and Triglycerides.
o https://chem.libretexts.org/Courses/University_of_Kentucky/UK%3A_CHE_103_-

_Chemistry_for_Allied_Health_%28Soult%29/Chapters/Chapter_14%3A_Biological_Molecules/14.2%3A_Lipids_and_Triglycerides
4. NutrientsReview. (2016). Glucose.
o https://www.nutrientsreview.com/carbs/monosaccharides-glucose.html
5. Sagar Aryal. ( 11 May 2021 ). Plastids- Definition, Structure, Types, Functions And Diagram.
o https://microbenotes.com/plastids-types-structure-and-functions/
6. Anupama Sapkota.(18 February 2022). Cell Organelles- Definition, Structure, Functions, Diagram.
o https://microbenotes.com/cell-organelles/
7. Belgarath007. (28 April 2007). Formation du maltose.
o https://commons.wikimedia.org/wiki/File:Formation_du_maltose.PNG
8. Anynomous . (n.d.). Digestion and Absorption in Animal.
o https://www.vedantu.com/question-answer/the-digestion-of-cellulose-in-rabbit-and-other-class-12-biology-cbse-5fa21ed4e5a3730cf2caf748
9. Anynomous. (2022). Structure of the Chloroplast.
o https://www.nagwa.com/en/explainers/812162636509/

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